Our methods paper on AC/PC to MNI conversion has been summarized in the following resources:

Furthermore, the methodology is described in the paper listed below.

Horn, A., Kühn, A. A., Merkl, A., Shih, L., Alterman, R., & Fox, M. (2017). Probabilistic conversion of neurosurgical DBS electrode coordinates into MNI space. NeuroImage, 150, 395–404. 

The methodology is implemented in the AC/PC conversion tool supplied within Lead-DBS.

Tools menu used to open the AC/PC to MNI conversion tool

AC/PC to MNI coordinate conversion tool as implemented in Lead-DBS. The warps are based on selected subjects/patients that must be normalized using Lead-DBS first. Alternatively, the open license IXI-Dataset may be used to perform conversions and Lead-DBS will selected subjects matched for age as described in Horn et al. 2017.